A subpopulation analysis of the phase 2 ADHERE trial suggests clinical benefit and a favorable safety profile for efgartigimod PH20 in Chinese patients with chronic inflammatory demyelinating polyneuropathy.
In a recently published subpopulation analysis of the phase 2 ADHERE trial (NCT04281472), treatment with
ADHERE enrolled 58 participants from mainland China in Stage A, with 47 participants randomized in Stage B (efgartigimod PH20, n = 21; placebo, n = 26). In Stage A, 77.6% (45/58; 95% CI, 64.7%–87.5%) of participants achieved confirmed evidence of clinical improvement (ECI). Rates of confirmed ECI were 86.4% (19/22; 95% CI, 65.1%–97.1%) in the treatment-naïve subgroup, 73.7% (14/19; 95% CI, 48.8%–90.9%) in participants with prior corticosteroid use, and 70.6% (12/17; 95% CI, 44.0%–89.7%) in those with prior intravenous immunoglobulin exposure.
In Stage B, clinical deterioration occurred in 28.6% (6/21) of participants in the efgartigimod PH20 group compared with 61.5% (16/26) in the placebo group, yielding an absolute difference of −33.0% (95% CI, −57.9% to −2.5%). Median time to clinical deterioration was not reached in the efgartigimod PH20 group and was 113.0 days (95% CI, 43.0–181.0 days) in the placebo group. Notably, treatment with efgartigimod PH20 was associated with a 68.7% reduction in the risk of clinical deterioration compared with placebo (hazard ratio, 0.313; 95% CI, 0.109–0.905).
“This subpopulation analysis indicates that efgartigimod PH20 is anticipated to be an effective, well-tolerated, and convenient treatment option for Chinese CIDP patients. Although cross-studies comparisons are challenging and should be viewed cautiously, the efficacy of efgartigimod PH20 in treating CIDP appears to be comparable to, if not better than, the two commonly used first-line treatments in Chinese CIDP patients,” lead author Jie Lin, MD, associate professor in the Department of Neurology at Fudan University, and colleagues wrote.1
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Participants who achieved confirmed ECI were then randomized in Stage B to receive double-blind treatment with either efgartigimod or placebo on a weekly basis for up to 48 weeks. The primary end points of the trial were the proportion of participants achieving confirmed ECI in Stage A and time to clinical deterioration in Stage B, as assessed using the adjusted Inflammatory Neuropathy Cause and Treatment score. Safety end points included incidences of treatment-emergent adverse events (TEAEs), discontinuations because of TEAEs, serious TEAEs and clinically significant laboratory abnormalities in both stages.
In Stage A, 49 of 58 participants (84.5%) reported at least 1 TEAE, with 31 (53.4%) experiencing TEAEs considered related to efgartigimod PH20. The most frequently reported TEAEs were upper respiratory tract infection, increased alanine aminotransferase, and increased blood triglycerides, each occurring in 5 participants (8.6%). Most TEAEs were grade 1 or 2; grade more than or equal to 3 TEAEs occurred in 3 participants (5.2%), and no grade 4 or 5 TEAEs were reported. One participant (1.7%) experienced a serious TEAE considered related to treatment.
In Stage B, 16 of 21 efgartigimod PH20-treated participants (76.2%) and 18 of 26 participants (69.2%) on placebo experienced at least 1 TEAE. TEAEs occurring in more than or equal to 10% of participants included COVID-19 and upper respiratory tract infection. Most TEAEs were grade 1 or 2; grade more than or equal to 3 TEAEs occurred in 2 participants (9.5%) in the efgartigimod PH20 group and 1 participant (3.8%) in the placebo group. No grade 4 or 5 TEAEs occurred. One serious TEAE was reported in each group, and the only treatment-related serious TEAE was a CIDP event in the placebo group. No TEAEs led to treatment discontinuation in either Stage A or Stage B cohorts.
"A key limitation of this analysis is that the China subgroup analyzes were not adequately powered and not multiplicity-adjusted,” Lin et al noted.1 “Therefore, results of this subpopulation analysis should be interpreted with caution. However, given the substantial inclusion of Chinese CIDP patients, the results from this subpopulation analysis still provides valuable evidence to support regional clinical practice.”
